RESUMO
Severe, early-onset photoreceptor (PR) degeneration associated with MERTK mutations is thought to result from failed phagocytosis by retinal pigment epithelium (RPE). Notwithstanding, the severity and onset of PR degeneration in mouse models of Mertk ablation are determined by the hypomorphic expression or the loss of the Mertk paralog Tyro3. Here, we find that loss of Mertk and reduced expression/loss of Tyro3 led to RPE inflammation even before eye-opening. Incipient RPE inflammation cascaded to involve microglia activation and PR degeneration with monocyte infiltration. Inhibition of RPE inflammation with the JAK1/2 inhibitor ruxolitinib mitigated PR degeneration in Mertk-/- mice. Neither inflammation nor severe, early-onset PR degeneration was observed in mice with defective phagocytosis alone. Thus, inflammation drives severe, early-onset PR degeneration-associated with Mertk loss of function.
Assuntos
Degeneração Retiniana , Retinose Pigmentar , Camundongos , Animais , c-Mer Tirosina Quinase/genética , c-Mer Tirosina Quinase/metabolismo , Epitélio Pigmentado da Retina/metabolismo , Receptores Proteína Tirosina Quinases/genética , Receptores Proteína Tirosina Quinases/metabolismo , Proteínas Proto-Oncogênicas/genética , Proteínas Proto-Oncogênicas/metabolismo , Degeneração Retiniana/genética , Degeneração Retiniana/metabolismo , Retinose Pigmentar/genética , Retinose Pigmentar/metabolismo , Inflamação/genética , Inflamação/metabolismoRESUMO
Mutations in pre-mRNA splicing factors are the second most common cause of autosomal dominant retinitis pigmentosa, and a major cause of vision loss. The development of gene augmentation therapy for disease caused by mutations in PRPF31 necessitates defining pretreatment characteristics and disease progression of patients with PRPF31-related retinitis pigmentosa. We show rates of decline of visual field area -6.9% per year and 30-Hz flicker cone response of -9.2% per year, which are both similar to observed rates for retinitis pigmentosa. We hypothesize that RNA splicing factor retinitis pigmentosa will be amenable to treatment by AAV-mediated gene therapy, and that understanding the clinical progression rates of PRPF31 retinitis pigmentosa will help with the design of gene therapy clinical trials.
Assuntos
Proteínas do Olho/genética , Mutação , Retinose Pigmentar/genética , Dependovirus/genética , Terapia Genética , Vetores Genéticos , Humanos , Splicing de RNA/genética , Retinose Pigmentar/diagnóstico , Retinose Pigmentar/terapiaRESUMO
Occlusion of the microvasculature by blood clots, atheromatous fragments, or circulating debris is a frequent phenomenon in most human organs. Emboli are cleared from the microvasculature by hemodynamic pressure and the fibrinolytic system. An alternative mechanism of clearance is angiophagy, in which emboli are engulfed by the endothelium and translocate through the microvascular wall. We report that endothelial lamellipodia surround emboli within hours of occlusion, markedly reducing hemodynamic washout and tissue plasminogen activator-mediated fibrinolysis in mice. Over the next few days, emboli are completely engulfed by the endothelium and extravasated into the perivascular space, leading to vessel recanalization and blood flow reestablishment. We find that this mechanism is not limited to the brain, as previously thought, but also occurs in the heart, retina, kidney, and lung. In the lung, emboli cross into the alveolar space where they are degraded by macrophages, whereas in the kidney, they enter the renal tubules, constituting potential routes for permanent removal of circulating debris. Retina photography and angiography in patients with embolic occlusions provide indirect evidence suggesting that angiophagy may also occur in humans. Thus, angiophagy appears to be a ubiquitous mechanism that could be a therapeutic target with broad implications in vascular occlusive disorders. Given its biphasic nature-initially causing embolus retention, and subsequently driving embolus extravasation-it is likely that different therapeutic strategies will be required during these distinct post-occlusion time windows.
Assuntos
Embolia/patologia , Fagocitose , Vasos Retinianos/patologia , Animais , Encéfalo/irrigação sanguínea , Circulação Cerebrovascular/fisiologia , Circulação Coronária , Fibrina/química , Fibrinólise , Fundo de Olho , Proteínas de Fluorescência Verde/metabolismo , Hemodinâmica , Humanos , Túbulos Renais/irrigação sanguínea , Pulmão/irrigação sanguínea , Macrófagos/citologia , Camundongos , Camundongos Transgênicos , Microcirculação , Microglia/metabolismo , Microscopia Eletrônica de Transmissão , Microvasos , Monócitos/citologia , Retina/metabolismo , TromboseRESUMO
Wnt/Wingless signal transduction directs fundamental developmental processes, and upon hyperactivation triggers colorectal adenoma/carcinoma formation. Responses to Wnt stimulation are cell specific and diverse; yet, how cell context modulates Wnt signalling outcome remains obscure. In a Drosophila genetic screen for components that promote Wingless signalling, we identified Earthbound 1 (Ebd1), a novel member in a protein family containing Centromere Binding Protein B (CENPB)-type DNA binding domains. Ebd1 is expressed in only a subset of Wingless responsive cell types, and is required for only a limited number of Wingless-dependent processes. In addition, Ebd1 shares sequence similarity and can be functionally replaced with the human CENPB domain protein Jerky, previously implicated in juvenile myoclonic epilepsy development. Both Jerky and Ebd1 interact directly with the Wnt/Wingless pathway transcriptional co-activators ß-catenin/Armadillo and T-cell factor (TCF). In colon carcinoma cells, Jerky facilitates Wnt signalling by promoting association of ß-catenin with TCF and recruitment of ß-catenin to chromatin. These findings indicate that tissue-restricted transcriptional co-activators facilitate cell-specific Wnt/Wingless signalling responses by modulating ß-catenin-TCF activity.